Tag: Maryland

Research Roundup: Combating jamming and spoofing

GNSS researchers presented hundreds of papers at the 2023 Institute of Navigation (ION) GNSS+ conference, which took place Sept. 11-15, 2023, in Denver, Colorado, and virtually. The following four papers focused on ways to combat GNSS jamming and spoofing. The papers are available here.

GPS World will be attending this year’s ION conference in Baltimore, Maryland on Sept. 16-20.

Photo: Who_I_amWho_I_am / iStock / Getty Images Plus / Getty Images

Optimal INS

The civil infrastructures behind safety-critical applications in aviation, maritime and terrestrial navigation rely heavily on global navigation satellite system (GNSS) signals. The civil GNSS signal structures are vulnerable to spoofing attacks, which can endanger public safety.

In this work, the authors introduced an optimal cumulative position-domain innovation (CPI) monitor to detect spoofing by accumulating tracking errors embedded in the spoofer’s signal. The authors also derived relationships between missed detection probability, tracking error magnitude and monitor run time to show that even with decimeter-level tracking error, the monitor can detect spoofing with a low probability of missed detection in less than 1 minute.

The team of researchers evaluated the performance of the CPI monitor for both white and time-correlated (colored) tracking errors. To compute protection levels and detect short-duration spoofing, researchers proposed a complementary solution separation (SS) monitor to implement in sequential, overlapping windows to compare the integrated INS/GNSS position solution against an inertial navigation system (INS) coasting solution. The INS-only coasting element allows the system to maintain positioning continuity after detection, albeit at lower accuracy, as the INS drifts.

The experimental results indicate that implementing a CPI monitor can dismiss the conjecture that INS-based spoofing detection is susceptible to slowly deviating counterfeit signals. It was found that if the duration of the spoofing event exceeds a minimum time defined by the variance and time constant of the tracking error, the spoofer’s target tracking error can be detected.

Birendra Kujur, Samer Khanafseh and Boris Pervan; “Optimal INS Monitor for GNSS Spoofer Tracking Error Detection.”

Space-Time Adaptive Processing

Antenna arrays and spatial processing techniques are among the most effective countermeasures against GNSS signal interference. In this paper, the authors propose a new array concept, space-time adaptive processing (STAP), that consists of spatially distributed subarrays small enough to fit inside the non-metallic parts of an automobile. The device is designed to be installed in bumpers or side mirrors.

During the experimental testing, the authors used beamforming algorithms for the array to perform against jammers in the GPS L5 and Galileo E5a bands. The authors composed a GNSS jamming scenario to compare conventional space adaptive processing (SAP) methods and the new STAP method using real-life measurements in a dynamic scenario. In this simulation, the car was rotated 360° throughout the complete measurement. The comparison between the received signal quality demonstrated an improvement for wideband signals.

The results demonstrate that the performance of the STAP was dependent on the number of taps analyzed in the testing simulation that included different fractional delays. Overall, the research showed STAP could outperform SAP implementation in applications requiring robust tracking, as it was able to process all satellites for an additional 12 seconds.

Marius Brachvogel, Michael Niestroj, Michael Meurer, Syed N. Hasnain, Ralf Stephan and Matthias A. Hein; “Space-Time Adaptive Processing as a Solution for Mitigating Interference Using Spatially-Distributed Antenna Arrays.”

Enabling RTK Positioning Under Jamming

New GNSS applications demand high position accuracy and resilience against radio frequency interference. Separately, these demands can be fulfilled by multi-antenna systems using spatial filtering and carrier-phase positioning algorithms, such as real-time kinematics (RTK), respectively. However, combining these approaches creates a severe issue: the spatial filtering induces a phase offset into the measured carrier phase leading to a loss of position accuracy.

This paper presents a new approach to compensate for the phase offset without knowing the antenna array radiation pattern or the direction of arrival of the signals. The proposed algorithm was tested in two different scenarios using an in-house software receiver in combination with the RTKlib — an open-source program package for GNSS positioning — that was used to estimate an RTK solution. In the first scenario, the signal power of a jammer from a constant direction of arrival (DoA) was raised stepwise. In the second scenario, a jammer with constant signal power was moved around the receiver antenna array. For both scenarios, the proposed algorithm was compared with a multi-antenna system not compensating for the phase bias and with a single antenna processing.

It is most suitable in situations where a medium-to-high precision (dm to cm) solution must be resilient to interference. A very high precision solution (cm to mm), comparable with a geodetic receiver accounting for antenna phase center variations, cannot be achieved with this algorithm.

In this paper, the signal recording and processing time was limited to less than half an hour. The carrier-phase offset produced by the proposed algorithm may become larger over longer observation times. Evaluating this is part of future work.

Tobias Bamberg, Andriy Konovaltsev and Michael Meurer; “Enabling RTK Positioning Under Jamming: Mitigation of Carrier-Phase Distortions Induced by Blind Spatial Filtering.”

Multi-layered Multi-Constellation GNSS Interference Mitigation

Several layers of defense can be implemented in a GNSS receiver to improve its performance in the presence of interference. These layers include the use of pre-correlation mitigation techniques, post-correlation quality indicators to screen measurements and fault detection and exclusion (FDE) at the position solution level.

This paper provides a characterization of the interactions between these layers of interference mitigation and a measurement quality check. Data collected in the presence of increasing levels of jamming were processed using different interference mitigation techniques, including robust interference mitigation (RIM) and the adaptive notch filter (ANF). A software-defined radio (SDR) approach was used, and measurements were generated by considering five interference-mitigation techniques. Position solutions were then computed using a forward-backward approach for receiver autonomous integrity monitoring (RAIM). Signals from GPS, Galileo and BeiDou were processed and both single and dual-constellation solutions were analyzed.

The results demonstrated that interference mitigation allowed the receiver to track a larger number of signals even in the presence of high levels of jamming power. This increased measurement availability was then effectively exploited by RAIM techniques to provide more reliable solutions. Measurements from several constellations further improved the reliable availability of the position solutions.

Ciro Gioia and Daniele Borio; “Multi-layered Multi-Constellation Global Navigation Satellite System Interference Mitigation.”

March 15, 2024
How public safety GIS saves us when disaster strikes
Tenacity of spirit is one of the great virtues. Supporters of geospatial technology have often had to endure steadfast resolve convincing others of the multi-dimensional value GIS provides. It is a battle best won by seeing and doing rather than by words.

Jack Maple proved the value of GIS to public safety in the early 1990s by using it to fight crime. But, in the context of firefighting and disaster operations, GIS had not been used.

Then, in the early 2000s, due in large part to 9/11, the government’s interest in GIS increased.

It was a necessary evolution. Technologies at the time were rapidly advancing. Computer graphics, computer processing power, the internet, shared databases, GPS, digital imagery, and mobile devices needed to merge. GIS was the only solution to bring them all together.

At the same time, disasters became increasingly destructive. Public safety and emergency management needed solutions, but most of the funding is by the government with tight budgets, so investments into geospatial technologies and specialized staff were limited.

It wasn’t until 2010 that FEMA hired the first Geospatial Information Officer. And, the Geospatial Data Act did not become law until 2018. The need was there but not the resources.

A small group of individuals saw that gap and together they began providing support to the public safety sector. The first organization they were able to work with was the National Association of State Fire Marshalls. Word quickly spread. Soon, other organizations began asking for geospatial services.

Eventually, 11 national organizations came together to provide support, structure and purpose for the fledgling team of GIS volunteers. This group became the founders of the National Alliance for Public Safety GIS (NAPSG) Foundation.

Now, 15 years later, NAPSG has contributed to recovery after every major disaster and many minor ones throughout the United States. Its success extends internationally — NAPSG has helped other countries set up their own public safety GIS support teams.

Image: NAPSG

Membership in NAPSG has grown to more than 65,000. Its members are involved in supporting operations for fires, flooding, search and rescue, earthquakes, storm and tornado damage, health crises, chemical spills, and more. They have become central to emergency management operations, helping coordinate efforts of multiple groups through GIS platforms.

During and after events, NAPSG hosts debriefs to evaluate and improve ongoing and future operations. The result advances the field of public safety. NAPSG also provides education to its constituent communities and makes its training available to the public.

NAPSG and its members are highly valued. Every state GIS council has the group as a point of contact. NAPSG is a trusted entity at the community level up through to the highest levels of the federal government, and they are one of the first calls FEMA makes in a crisis.

Tari Martin

I had the opportunity to interview Tari Martin (GISP), the director of national and federal programs, one of the leaders in NAPSG. Speaking with Tari made me realize that GIS is still early in its adoption phase. Tari is one of the founders of GIS at the state level. Earlier in her career she was the first person in the state of Maryland dedicated to supporting emergency management operations.

She helped build Maryland’s emergency management framework coordinated efforts with the National Incident Management System (NIMS), and she began pulling in federal data such as the Homeland Infrastructure Foundation-Level Dataset (HIFLD) for use in local operations.

Now, Tari serves on the Maryland GIS Council for the Public Safety/Next Generation 911 Subcommittee in addition to her regular duties as a director for NAPSG. Tari also serves as a program manager, working to create a universal symbology for public safety and emergency management.

Maps and map symbology are revered. Map symbology emerged from a long, proud, history of cartography dating back to a time before the Golden Age of Exploration when maps were adorned with beautiful, hand-drawn symbols of wind roses, sea creatures, and exotic plants and animals; including inscriptions, such as that within the cartouche of the Typus Orbis Terrarum (Atlas of the World) by Ortelius in 1573. Therein are inscribed the words from Cicero’s Tusculan Disputations, “Quid ei potest videri magnum in rebus humanis, cui aeternitas omnis, totiusque mundi nota sit magnitudo,” which translated means, “For what human affairs can seem important to a person who keeps all eternity before his eyes and knows the vastness of the universe?”

Map symbology has been more an art than a science driven predominantly to support specific purposes, such as navigation, war, surveying, mining, construction and recreation. Additionally, symbologies may not translate across professions, regions or cultures. Even when the symbols are the same, the colors may be different giving symbols different meanings.

Symbols are a visual language, and as the world becomes increasingly smaller and emergency events more international, the need for the language of maps to become universal is necessary. NAPSG has taken on that challenge, coordinating input from multiple stakeholders.

In essence, NAPSG is working with groups like Urban and Regional Information Systems Association (URISA) to create the Rosetta Stone of map symbology for public safety and emergency management, and Tari Martin is one of the central figures working on that project. The symbol library is free and publicly available on the NAPSG website.

Tari also reminisced about her early days when she first got into GIS just before Hurricane Katrina, and how many of her co-workers in Maryland mobilized to go down and help out with recovery operations. She stated that was one of the moments in her career that cemented her understanding for the value of GIS in post-disaster operations. Tari now teaches a course on GIS in Emergency Management for URISA.

NAPSG is involved in cutting-edge technologies helping to shape and educate the public safety community. Its members are working with autonomous vehicles, indoor mapping technologies, augmented reality and virtual reality, wearables, and other opportunities as they arise.

NAPSG makes its content available online. Explore its best practices, guidance and standards, education and training, events, qualifications and credentialing, toolkits and more. Become a NAPSG member at no cost.

Prior articles referenced:
William Tewelow works for the Federal Aviation Administration. He is a graduate of the FAA management fellowship program and while on special assignment to the U.S. Department of Transportation William led a national strategic geospatial project for the White House Open Data Partnership. He is a Geographic Information Systems Professional (GISP) and a Maryland STEMnet Scholar Speaker. He has degrees in Geographic Information Technology and Intelligence Studies, and is currently pursuing a masters degree in Organizational Management. He was among the first in the nation to earn a Geospatial Specialist Certification from the U.S. Department of Labor while working at NASA Stennis Space Center.

William retired from the U.S. Navy after serving 23 years as a Geospatial and Imagery Intelligence Specialist, a Naval Aviator, a Meteorologist, and a Tactical Oceanographer. He is married, enjoys writing, traveling, solving problems, and is fascinated by new technology and historical context. His favorite quote is, “A man’s mind changed by a new idea can never go back to its original dimension.” ~ Oliver Wendell Holmes
November 11, 2020
Robotic Research innovates to help fight COVID-19

D.C.-area engineering firm produces reusable face shields for region’s hospitals, offers sterile 3D printer patent for COVID applications globally

The team of engineers at Robotic Research LLC, based in Clarksburg, Maryland, is applying its innovative engineering expertise to create new solutions for healthcare workers to help fight the COVID-19 crisis in the Washington area and around the world.

Robotic Research is a provider of autonomy and robotic technologies for government and commercial customers.

The company has created a unique design for reusable face shields and is providing the shields to healthcare teams in hospitals around the Greater Washington Metro area. The company also just opened up its patented design of its sterile 3D printer by waiving licensing fees globally for any application of the printers related to fighting the current public health pandemic.

Face shields

Face shield printed for health-care workers to help fight COVID-19. (Photo: Robotic Research)

The face shields, which Robotic Research is printing on standard industrial 3D printers at its robotics engineering facility in Clarksburg, are being delivered to support teams at hospitals in the Montgomery County area.

The face shield design provides comfort and protection, and features an improved disinfection process capability using materials compatible with hospital cleaning methods. The design has been approved for use in select departments, with broader uses under evaluation.

“Our team wanted to help out in any way we could to support the local frontline health-care providers who are working around the clock to assist those impacted by the COVID-19 public health crisis,” said Alberto Lacaze, president of Robotic Research. “We are producing a face shield that modifies a design based off the blueprint provided by the National Institutes of Health. The design includes some enhancements to further protect from aerosol in the temple area and allow the masks to be cleaned and therefore reusable, as well as comfortable to wear over prolonged use.”

Robotic Research has sourced materials from across the country to support the production of approximately 2,000 face shields. The company is seeking a grant through Montgomery County and the state of Maryland to boost production to approximately 500 shields a day. The company normally uses its standard 3D printers to support many of its robotic products and solutions.

Sterile 3D printer

A batch of face shields prepared fo delivered to a Maryland hospital. (Photo: Robotic Research)

Materials used for polymer 3D printing are often damaged by the high temperatures, chemicals or radiation used in standard sterilization processes. Robotic Research’s patented process overcomes this challenge by using a sterile chamber around a 3D printer where unsterilized plastic is brought into the chamber.

The possibly contaminated plastic is sterilized by the printing process and packaged maintaining the sterile field.

This system was initially designed for a U.S. government agency to allow sterile medical materials to be printed at locations where commonly used sterilization methods might not be possible.

“Because this printer can create sterile materials, which are sterile from the inside out once produced, we are eliminating the need for hospitals to re-sterilize equipment before use,” Lacaze said. “At a time when efficiency and supplies are critical, we hope this technology will be able to help alleviate some of the immense pressure hospitals and medical facilities are currently facing. It is our hope that providing the use of this process at no cost may help bring solutions to the health care teams working to save lives during this crisis.”

The unique printer process enables the manufacturing of sterile medical equipment and implantable device components, such as intubation tubes and other materials required during invasive procedures, in a manner that eliminates the need for additional sterilization.

Robotic Research’s patented sterile 3D printing process (USPTO 10,406,758) will be available royalty-free for a minimum of one year for any COVID-19 applications across the globe.

The company is committed to continuing to use its resources and facilities to develop solutions for the ongoing challenges of the COVID-19 pandemic.

April 15, 2020
North Dakota, Delaware and Maryland Quads Updated

The latest North Dakota, Delaware and Maryland Quads are now available from the United States Geological Survey.

The new US Topo maps for North Dakota (1,402 maps), Delaware (38 maps) and Maryland (213 maps) have been posted to the USGS Map Locator & Downloader and are also accessible through The National Map viewer.

The new maps feature a design that was launched earlier this year and replace the first edition US Topo maps for those states. The new design presents a crisper and cleaner presentation, which enhances the readability of the maps for online and printer use.

June 5, 2014